1. Field of the Invention
The present invention relates generally to the manufacture and deployment of orbital spacecraft, and more particularly to the manufacture of spacecraft using functional modules and the deployment of such spacecraft using conventional launch vehicles.
2. Related Art
The deployment of orbital spacecraft incurs substantial costs. One source of these costs arises from the nonrecurring costs of designing, developing and manufacturing entirely new spacecraft for each new mission. To alleviate these costs, manufacturers have turned to the use of standard spacecraft busses. A spacecraft bus includes all of the subsystems required to support a payload. Common bus subsystems include those for electrical power, attitude knowledge and control, communication, propulsion, thermal management, onboard processing, and structure. Under this approach, a single spacecraft bus can support a variety of mission payloads without substantial nonrecurring bus-related costs for each mission.
Such monolithic spacecraft busses are generally manufactured in a centralized process resembling an automobile assembly line. One disadvantage of this approach is that it features a single critical path. If a problem occurs with any bus on the assembly line, the line must be halted until the problem is corrected. During this halt, most of the manufacturing equipment and personnel are forced to remain idle.
Another disadvantage of this centralized approach is that it is a slow one. One solution conventionally employed is to simply replicate the assembly line so that multiple assembly lines can be operated simultaneously. Of course, each individual assembly line is prone to the problem described above. Another flaw in this solution is that the replication of assembly lines requires duplication of manufacturing equipment and staffing of additional personnel, thereby multiplying the cost of the manufacturing process.
Another significant cost arises from the use of launch vehicles to deploy spacecraft in orbit. The prevailing trend is to launch spacecraft using expendable launch vehicles such as the Atlas, Proton, and Delta II rockets. The spacecraft are mounted inside the fairing at the top of the vehicle for transport to orbit. During the ascent phase of the launch, or after reaching the desired orbit, the spacecraft are deployed.
One way to minimize the per-spacecraft launch cost is to maximize the number of spacecraft that can be mounted within a launch vehicle fairing. Some efforts have concentrated on optimizing the cross-sectional size and shape of the spacecraft to fit a particular fairing. Unfortunately, conventional cross sections that are optimized for a particular launch vehicle are not well-suited for other launch vehicles.